Ferrites are a type of novel non-metallic magnetic materials, widely used in areas such as broadcasting communication, navigation radar, cosmic navigation, medicine and biology. Since the 1940's, knowledge of the materials has developed rapidly and they have been widely applied. Ferrites are mixed oxides composed of iron and other one or two metals, such as spinel ferrites with the chemical formula MeFe2O4, wherein Me is a divalent ion (Mn2+, Zn2+, Cu2+, Ni2+, Mg2+, Co2+, etc.) which has similar ionic radius to the divalent iron ion. Therefore, various spinel ferrites with binary- or multi-component ions can be obtained by changing the identity and amount of metal ions.
At present, ferrites are synthesized mainly via the calcination of mixtures of metal oxides or hydroxides or other precipitated mixtures. Because of poor activity, low mixture uniformity and large particle sizes in the cases of these raw materials as calcination precursors, there are some shortcomings in this preparation process such as it being difficult to ensure complete reaction and poor sample uniformity. Faced with this situation, others have modified the preparation art. In the papers of C. Jovalekic, M. Zdujic, A. Radakovic, and M. Mitic., Mater. Lett. 24, 365 (1995) and J. Ding, H. Yang, W. F. Miao, P. G. McCormick, and R. Street., J. Alloys Compd. 221, 959 (1995), nano spinel ferrites with dispersion of cations differing from that obtained by traditional methods were synthesized through high energy grinding. However, due to use of mixtures of materials as calcination precursors and the lack of mixture uniformity it is very difficult to further improve the magnetic properties of the ferrites.